{if isset($topic) && !isset($cat) && !isset($sub) && $topic.descriptif != ""}
    <div id="desc_shop">
    {$topic.descriptif}
    </div>
{elseif isset($cat) && !isset($sub) && $cat.description != ""}
    <div id="desc_shop">
    {$cat.description}
    </div>
{elseif isset($sub) && $sub.description != ""}
    <div id="desc_shop">
    {$sub.description}
    </div>
{/if}